According to established customs or tradition it is common to engrave decorations of any design upon the metal sections of many arms, such as, for example, shotguns, pistols, revolvers, and the like.
Presently, the practice of making such decorative engravings is accomplished mechanically by copy pantographing, pressure rollers, or other similar equipment.
Particularly, such decorations are presently made by means of pressure roller machines, wherein the engraving matrices are made by means of a relief process upon cylindrical rollers which, when pressed upon or against the metal surfaces to be processed, will impress the decorative designs thereon.
However, while such operations may be accomplished quite rapidly, and accordingly such processes are advantageous from an economical viewpoint, the systems suffer from some substantial disadvantages deleteriously affecting the grade or quality of the finshed product and the cost thereof.
One of the disadvantages of the aforenoted systems is that in order to obtain such engravings, considerable pressure must be imposed upon the rollers in order to provide for deep penetration of the relieved matrices into and throughout the surface strip of the metal workpieces. In addition, this also requires the provision of machines having a somewhat rigid structure, and the use of skilled labor or additional servomechanisms to achieve the high pressures required.
Another disadvantage of the aforenoted systems is that while the high pressure developed between the rollers and the surfaces to be processed serves to provide deep engravings upon the workpieces, such pressures also tend to develop bulges or protuberances within the engraved metal parts. These irregular bulges or protuberances appear upon all of the engraved surfaces, and consequently, such quite obviously substantially impair the grade and value of the pieces being processed.
Still another disadvantage of the aforenoted systems is the fact that the same cannot be satisfactorily employed for processing workpieces having rounded pattern surfaces. When so employed, the engravings appear to be clearer and deeper at the central area of the workpieces and merely superficial within the vicinity of the rounded side edges of the workpieces due to a decrease in the pressure developed between the roller and the workpiece within the side edge regions of the workpiece as defined by the contact planes or surfaces of the roller and the workpiece.